It is believed that the pertinent state-of-the-art is represented by: U.S. Pat. Nos. 4,649,911, 3,387,607, 4,110,419, 4,303,601, 5,769,071, 5,267,555 7,228,859 and 7,523,751; French patent/s or patent application/s Ser. Nos 4029781, 661696, 19541483 and 4109269; French patent Ser. No. 2543442; GB patent 1359280; Japanese patent publications Ser. No. 2010240189, 5345027 and 5000162; Chinese patents/utility models 2083936U, 2146252Y, 201020125Y 2822668Y and 2535068Y; Canadian patent application CA2689364 as well as by international patent applications having publication No. WO0054892 and WO2008036801.